BBC Scotland chief sports writer Tom English-
“This has come as a major surprise. I talked to somebody close to McKay who had spoken with him in the last three days and was given no indication this was in the pipeline. Everyone has been blindsided by it.
This was a dream job for McKay, a Celtic fan all his days. He was effusive when given the job and totally absorbed in it.
He had been at Scottish Rugby for 13 years but saw this as the big step up, the one he wanted. It's now over in 71 days.
Celtic will wait to get who they consider the right person to replace him.”